This example visualizes the Iris dataset with a scatter plot that encodes sepal length on the x-axis, petal length on the y-axis, and species using distinct point shapes. It demonstrates modular D3 v7 code organization with local ES6 modules for axes, scatter plot rendering, and a custom shape legend. The visualization uses `d3.scaleLinear`, `d3.scaleOrdinal`, `d3.symbol`, and `d3.axisLeft`/`d3.axisBottom`. Data loads asynchronously via `fetch` and `d3.csvParse`, with points rendered as SVG paths using the d3 symbol generator.